// Package log provides debug logging
package log

import (
	"fmt"
	"os"
)

var (
	// logger is default Logger
	logger Logger = NewLogger()
	// default log level is info
	level = LevelInfo
	// prefix for all messages
	prefix string
)

// Logger is event logger
type Logger interface {
	// Read reads specified number of log entries
	Read(int) []interface{}
	// Write writes logs to logger
	Write(...interface{})
}

// level is a log level
type Level int

const (
	LevelFatal Level = iota
	LevelError
	LevelInfo
	LevelWarn
	LevelDebug
	LevelTrace
)

func init() {
	switch os.Getenv("MICRO_LOG_LEVEL") {
	case "trace":
		level = LevelTrace
	case "debug":
		level = LevelDebug
	case "warn":
		level = LevelWarn
	case "info":
		level = LevelInfo
	case "error":
		level = LevelError
	case "fatal":
		level = LevelFatal
	}
}

func Log(v ...interface{}) {
	if len(prefix) > 0 {
		logger.Write(fmt.Sprint(append([]interface{}{prefix, " "}, v...)...))
		return
	}
	logger.Write(fmt.Sprint(v...))
}

func Logf(format string, v ...interface{}) {
	if len(prefix) > 0 {
		format = prefix + " " + format
	}
	logger.Write(fmt.Sprintf(format, v...))
}

// WithLevel logs with the level specified
func WithLevel(l Level, v ...interface{}) {
	if l > level {
		return
	}
	Log(v...)
}

// WithLevel logs with the level specified
func WithLevelf(l Level, format string, v ...interface{}) {
	if l > level {
		return
	}
	Logf(format, v...)
}

// Trace provides trace level logging
func Trace(v ...interface{}) {
	WithLevel(LevelTrace, v...)
}

// Tracef provides trace level logging
func Tracef(format string, v ...interface{}) {
	WithLevelf(LevelTrace, format, v...)
}

// Debug provides debug level logging
func Debug(v ...interface{}) {
	WithLevel(LevelDebug, v...)
}

// Debugf provides debug level logging
func Debugf(format string, v ...interface{}) {
	WithLevelf(LevelDebug, format, v...)
}

// Warn provides warn level logging
func Warn(v ...interface{}) {
	WithLevel(LevelWarn, v...)
}

// Warnf provides warn level logging
func Warnf(format string, v ...interface{}) {
	WithLevelf(LevelWarn, format, v...)
}

// Info provides info level logging
func Info(v ...interface{}) {
	WithLevel(LevelInfo, v...)
}

// Infof provides info level logging
func Infof(format string, v ...interface{}) {
	WithLevelf(LevelInfo, format, v...)
}

// Error provides warn level logging
func Error(v ...interface{}) {
	WithLevel(LevelError, v...)
}

// Errorf provides warn level logging
func Errorf(format string, v ...interface{}) {
	WithLevelf(LevelError, format, v...)
}

// Fatal logs with Log and then exits with os.Exit(1)
func Fatal(v ...interface{}) {
	WithLevel(LevelFatal, v...)
	os.Exit(1)
}

// Fatalf logs with Logf and then exits with os.Exit(1)
func Fatalf(format string, v ...interface{}) {
	WithLevelf(LevelFatal, format, v...)
	os.Exit(1)
}

// GetLogger returns the local logger
func GetLogger() Logger {
	return logger
}

// SetLevel sets the log level
func SetLevel(l Level) {
	level = l
}

// GetLevel returns the current level
func GetLevel() Level {
	return level
}

// Set a prefix for the logger
func SetPrefix(p string) {
	prefix = p
}

// Set service name
func Name(name string) {
	prefix = fmt.Sprintf("[%s]", name)
}